Cancer risk increases with advancing age in both men and women. The lifetime risk of developing a cancer in men is 44% and in women is 39% (175). Because only 1.5% of men and women live to 85 years, persons who are cancer free at that age are a small proportion of the total persons in their birth cohort. It is possible, therefore, that these elderly cancer-free persons carry genes that confer resistance to cancer development. This pilot study is designed to assess the feasibility of detecting cancer-resistance genes in healthy, cancer free elderly persons. Our genetic analyses will focus on Ashkenazi Jews, a population that has been well studied and that provides a rich source for the discovery of resistance genes using a linkage-disequilibrium (LD) mapping approach. Cancer-free Ashkenazi Jews (N=50) 85 or older will be identified, blood specimens will be collected, and DNA samples will be prepared. A comparison group (N=50) of Ashkenazi Jews who have developed colorectal cancer (CRC) will be identified amongst persons who had surgery at Memorial Hospital and will be matched to the cancer-free persons by birth year and sex. DNAs will be prepared for genotyping. Lifestyle characteristics-smoking, drinking, and diet-and family history will be studied as covariates. We will genotype the healthy elderly cases and CRC patients using a panel of 10,000 single nucleotide polymorphisms (SNPs) distributed evenly across the genome (median frequency of 1 SNP/225kb) using the Affymetrix 10,000 SNP array chip.